The present invention relates to pushbutton switches for use in electrical circuits and in particular to pushbutton switches in which electrical contact is either made or broken substantially simultaneously with a tactile and/or auditory signal from the switch as the switch plunger advances. In one embodiment this may be a momentary ON switch in which electrical contact is made upon advancing the plunger and contact is broken when the plunger retracts.
Pushbutton switches are well known in the art and examples thereof may be found in U.S. Pat. Nos. 3,694,603, 4,055,736, 4,175,222, 4,319,106, 4,345,128, 4,906,808, 5,132,499 and 5,226,529, the disclosures of which are incorporated herein by reference. The foregoing patents disclose pushbutton switches adapted to sequentially open and close an electrical circuit or to sequentially switch a common lead between two alternate portions of a circuit. In addition to the switches shown in the above patents, other designs are known in the art, having a variety of configurations, adapted for similar function.
In prior pushbutton switches having a plunger which advances a rotatable ratchet by camming action, the ratchet advances part of a turn upon advance of the plunger and then, upon release of the plunger, electrical contact is made as the plunger retracts. Upon the next actuation of the switch, electrical contact is broken. Such a switch is shown, for example, in U.S. Pat. No. 5,226,529. Such a switch may be used for an ON-OFF light switch, for example.
It is desirable, however, for electrical contact to be made or broken simultaneously with advance of the ratchet so that the switch operator either hears an audible click or feels a change in pressure on the plunger (or both) as the state of contact is changed. This is particularly desirable in a momentary ON switch where electrical contact is made upon advancing the plunger so that the operator knows when contact is made, and can then release the plunger. Such switches find utility in modern automotive applications where the pushbutton switch provides a momentary signal to a circuit that initiates some action, rather than the action being caused by current through the pushbutton switch directly. A "low tech" example of such signals occurs in some household doorbell systems where chimes continue to play after a momentary push on the doorbell has been released.